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  • Most common cause of focal encephalitis in patients with AIDS
  • Risk at CD4 < 100 and not on prophylaxis

Clinical Features

Differential Diagnosis

  • Lymphoma
    • More commonly single lesion in the periventricular white matter or corpus callosum
  • Cerebral TB
    • Characteristic inflammatory appearance with isodense exudate filling basal cisterns
  • Fungal infection

HIV associated conditions


  • Head CT without contrast
    • Shows multiple subcortical lesions with predilection for basal ganglia
    • Contrast usually not needed; if obtained, will show ring enhancing lesions
  • CSF
    • Helpful but high rate of false negatives
  • Serology not generally helpful since antibodies common in general population




Antibiotics only needed if patient has severe symptoms



  • Spiramycin 1 g orally every 8 hours[2]
    • If amniotic fluid is positive treat with 3 weeks of pyrimethamine (50 mg/day orally) + sulfadiazine (3 g/day orally in 2-3 divided doses)
    • Alternate with a 3-week course of Spiramycin 1 g 3 times daily OR
  • Pyrimethamine (25 mg/day orally) and sulfadiazine (4 g/day orally) divided 2 or 4 times daily until delivery AND
    • Leucovorin 10-25 mg/day orally to prevent bone marrow suppression


  • Consider dexamethasone 4mg IV q6hr for significant edema or mass effect

Folinic Acid

Administer if the treatment regimen includes Leucovorin


  • Admit


  1. Gutteridge, David L MD, MPH, Egan, Daniel J. MD. The HIV-Infected Adult Patient in The Emergency Department: The Changing Landscape of the Disease. Emergency Medicine Practice: An Evidence-Based Approach to Emergency Medicine. Vol 18, Num 2. Feb 2016.
  2. Paquet C, Yudin MH. Toxoplasmosis in pregnancy: prevention, screening, and treatment. J Obstet Gynaecol Can. Jan 2013;35(1):78-9.